[PATCH v3 09/12] perf, persistent: Use unique event ids

[Robert Richter]

From: Robert Richter <robert.rich...@linaro.org>

Tracepoints have a unique attr.config value. But, this is not
sufficient to support all event types. For this we need to generate
unique event ids.

Signed-off-by: Robert Richter <robert.rich...@linaro.org>
Signed-off-by: Robert Richter <r...@kernel.org>
---
 kernel/events/persistent.c | 40 ++++++++++++++++++++++++++++++++++++++--
 1 file changed, 38 insertions(+), 2 deletions(-)

diff --git a/kernel/events/persistent.c b/kernel/events/persistent.c
index aca1e98..f23270b 100644
--- a/kernel/events/persistent.c
+++ b/kernel/events/persistent.c
@@ -1,6 +1,7 @@
 #include <linux/slab.h>
 #include <linux/perf_event.h>
 #include <linux/ftrace_event.h>
+#include <linux/idr.h>
 
 #include "internal.h"
 
@@ -13,10 +14,37 @@ struct pevent {
        int             id;
 };
 
+static struct idr event_idr;
+static struct mutex event_lock;
 static struct pmu persistent_pmu;
 static DEFINE_PER_CPU(struct list_head, pevents);
 static DEFINE_PER_CPU(struct mutex, pevents_lock);
 
+static inline struct pevent *find_event(int id)
+{
+       struct pevent *pevent;
+       rcu_read_lock();
+       pevent = idr_find(&event_idr, id);
+       rcu_read_lock();
+       return pevent;
+}
+
+static inline int get_event_id(struct pevent *pevent)
+{
+       int event_id;
+       mutex_lock(&event_lock);
+       event_id = idr_alloc(&event_idr, pevent, 1, INT_MAX, GFP_KERNEL);
+       mutex_unlock(&event_lock);
+       return event_id;
+}
+
+static inline void put_event_id(int id)
+{
+       mutex_lock(&event_lock);
+       idr_remove(&event_idr, id);
+       mutex_unlock(&event_lock);
+}
+
 /* Must be protected with pevents_lock. */
 static struct perf_event *__pevent_find(int cpu, int id)
 {
@@ -128,13 +156,16 @@ persistent_open(char *name, struct perf_event_attr *attr, 
int nr_pages)
        struct pevent *pevent;
        char id_buf[32];
        int cpu;
-       int ret = 0;
+       int ret;
 
        pevent = kzalloc(sizeof(*pevent), GFP_KERNEL);
        if (!pevent)
                return -ENOMEM;
 
-       pevent->id = attr->config;
+       ret = get_event_id(pevent);
+       if (ret < 0)
+               goto fail;
+       pevent->id = ret;
 
        if (!name) {
                snprintf(id_buf, sizeof(id_buf), "%d", pevent->id);
@@ -163,6 +194,9 @@ persistent_open(char *name, struct perf_event_attr *attr, 
int nr_pages)
 fail:
        for_each_possible_cpu(cpu)
                persistent_event_close(cpu, pevent);
+
+       if (pevent->id)
+               put_event_id(pevent->id);
        kfree(pevent->name);
        kfree(pevent);
 
@@ -306,6 +340,8 @@ void __init perf_register_persistent(void)
 {
        int cpu;
 
+       idr_init(&event_idr);
+       mutex_init(&event_lock);
        perf_pmu_register(&persistent_pmu, "persistent", PERF_TYPE_PERSISTENT);
 
        for_each_possible_cpu(cpu) {
-- 
1.8.3.2

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/